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BP: Fachverband Biologische Physik

BP 9: Actin Dynamics

BP 9.1: Vortrag

Dienstag, 24. März 2009, 10:45–11:00, ZEU 260

Dynamics of the actin cytoskeleton in response to periodic stimuli — •Christian Westendorf¹, Eberhard Bodenschatz¹, and Carsten Beta^1,2 — ¹MPI für Dynamik und Selbstorganisation, Göttingen — ²Institut für Physik und Astronomie, Universität Potsdam

The dynamic properties of the actin cytoskeleton provide the basis for motility, phagocytosis, and division of eukaryotic cells. Polymerization of actin fibers within the branched cortical network exerts a force at the membrane of the leading edge resulting in the formation of pseudopods and, finally, cell motion. A widely used model system for the study of actin dynamics in vivo is the social amoeba Dictyostelium discoideum. It is the aim of this study to characterize intrinsic time scales of the actin cytoskeleton in chemotactic Dictyostelium cells. We observe filamentous actin using a LimE-GFP construct in an AX-2 background. Microfluidic techniques, including laser-mediated uncaging of caged cAMP, are used to expose single Dictyostelium cells to periodic stimuli of cAMP. Responses of the actin cytoskeleton were recorded by fluorescence imaging of LimE-GFP using confocal laser scanning microscopy. Based on frequency analysis, we find an optimal response regime of the actin system around 20 sec. For longer forcing periods, a frequency doubled resonant response could be observed. For short forcing periods no entrainment was found. We also performed computer automated celltracking on the cells exposed to periodic stimuli.